Mortgage Calculator (UK)
Price, deposit, rate, term — your monthly repayment and LTV, live.
How this is calculated
A UK repayment mortgage amortizes like any fixed-payment loan: the loan is the price minus your deposit, and the monthly payment comes from the standard formula:
M = P × r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) where P = price − deposit, r = rate ÷ 12, n = years × 12
Worked example: a £250,000 property with a £25,000 deposit (90% LTV) borrowed at 4.5% over 25 years gives a loan of £225,000 and a monthly repayment of about £1,251 — roughly £375,200 paid in total, of which about £150,200 is interest.
The two levers UK borrowers actually control
LTV band: lenders price in steps — crossing under 90%, 85%, 75%, or 60% LTV usually unlocks a cheaper product. In the example above, finding £12,500 more deposit moves you from 90% to 85% and reprices the entire loan. Term: stretching 25 to 35 years cuts the monthly payment but adds tens of thousands in interest — try it on the slider and watch the total-interest line, then decide with both numbers in view. Most fixes last 2–5 years, so re-run this page with a stressed rate (add 2–3%) to see what a remortgage at higher rates would mean before you commit.
Frequently asked questions
How is the monthly mortgage payment calculated?
With the standard repayment-mortgage formula M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1): P is the loan (price minus deposit), r the monthly rate (annual ÷ 12), n the number of monthly payments. It is the same amortization math UK lenders use for capital-repayment mortgages.
What is LTV and why does it matter?
Loan-to-value — the loan as a percentage of the property price, shown live in the result. UK lenders price by LTV band: dropping below 90%, 85%, 75%, or 60% typically unlocks a cheaper rate, so a slightly bigger deposit can cut the rate on the whole loan.
Fixed or variable — what does this calculator assume?
It computes the payment at the rate you enter, held for the whole term — which is how you compare deals. In practice most UK borrowers fix for 2–5 years and then remortgage; re-run the numbers with a different rate to see what a change would do to the payment.
Does this include stamp duty or fees?
No — it computes the mortgage payment itself. Budget separately for stamp duty (SDLT in England, LBTT in Scotland, LTT in Wales), legal fees, surveys, and any product fee, which is sometimes added to the loan.
Is anything I enter uploaded?
No. Prices, deposits, and rates are processed entirely in your browser — nothing is sent to a server, and the page keeps working offline once loaded.